The effect of low and high salt diets on the release and metabolism of inactive and active renin will be determined in the dog. We will also examine metabolism of active and inactive renin in those animals following acute stimulation or suppression of the renin-angiotensin system. Previous data suggested that conversion of inactive to active renin may take place in the circulation. Therefore, we will investigate conversion of inactive renin in the kidney and other vascular beds to determine where this conversion takes place. Furthermore, in vitro experiments will be performed to determine the characteristics of inactive renin release under a variety of conditions. Finally, since renal hylar lymph has been used to measure the concentration in the renal interstitial space, similar studies will be carried out to determine if inactive renin is present in renal hylar lymph.